Photographic element and process providing improved colour rendition

Abstract: A photographic element and process useful therewith comprises at least two light sensitive silver halide layers sensitized to green light and having differing degrees of light sensitivity, comprising in association with a higher sensitivity layer a yellow dye forming DIR coupler which releases a development inhibitor containing a weak inhibitor fragment, and further comprising in association with the lower sensitivity layer a cyan dye forming DIR coupler with a timing group containing a strong inhibitor fragment which releases a precursor of the development inhibitor fragment.

Description: Field of the Invention This invention relates to color photographic elements and processes which produce improved color rendition. Background of the Invention It has been desirable to improve the color rendition of photographic elements. More specifically, it is desirable to have the ability to inhibit the red- and the blue- sensitive layers to the desired degree as a function of green layer development. One method for improved color reproduction is through the use of colored couplers as described in U.S. Patents 4,163,670; 2,428,054; and 3,148,062. However, with this method of color correction, the nonexposed areas are highly colored which can lead to long printing times. Furthermore, in a multilayer structure where the layer arrangement is blue-sensitive, green-sensitive, and red-sensitive, with respect to the exposing light only a yellow colored coupler could be used in the green-sensitive layers or there would be a loss in red layer sensitivity. The use of "DIR" couplers or "development inhibitor releasing" couplers as defined in C. R. Barr, J. R. Thirtle, and P. W. Vittum, Photographic Science and Engineering, Vol. 13, 74N, 80 214-217 (1969),are generally known to provide interlayer effects and improve color reproduction through the imagewise release of inhibitor fragments. There are generally two types of inhibitor fragments: inhibitor fragments which strongly adsorb to silver and greatly suppress development (strong inhibitors) and inhibitor fragments which weakly adsorb to silver and suppress development to a lesser degree (weak inhibitors). Both types of inhibitor fragments can be linked to the coupler through a timing group which allows the inhibitor precursor to diffuse. However, DIRs linked through a timing group to a pyrazolone nucleus are unstable and costly to manufacture. Therefore, there is a need to have DIR compounds in the green sensitive layers which overcome the existing deficiencies. There have been numerous attempts to define layer arrangements incorporating DIRs of various types. For example, U.S. Patent 4,804,619 discloses the use of diffusible DIRs in a highest green-sensitive layer of a specified layer thickness. The inhibitor fragment released from the DIR may be diffusible because of its weak inhibiting ability or may be linked through a timing group to permit it to diffuse. However, no particular combination of DIRs to be used in the fast and in the slower layers is disclosed. U.S. Patent 4,414,308 teaches the inclusion of a DIR with a timing group in the fast, the slow and/or an intermediate nonsensitive layer of a multilayer pack. No particular arrangement of layers nor combination of DIRs is suggested. EP-A-0476327 suggests the use of a triple-coated green sensitive layer having the same DIR coupler in the highest and mid-sensitive layers. No suggestion of providing a certain type of DIR in a higher sensitivity layer and another type of DIR in a lower sensitivity layer is made. Other U.S. patents that deal with the use of DIRs in multilayer applications are the following: U.S. 4,963,465; U.S. 4,145,219; U.S. 4,273,861; U.S. 4,670,375; and U.S. 4,564,587. None of the disclosed arrangements provide the desired effect of green light on the red and blue records so as to improve the color rendition sufficiently. It is therefore a problem to be solved to provide a photographic element and process which provide improved color rendition through the ability to inhibit the red- and blue-sensitive layers to the desired degree as a function of the development of the green-sensitive layers-through the incorporation of a specified combination of DIRs. Summary of the Invention A photographic element and process useful therewith comprises at least two light sensitive silver halide layers sensitized to green light and having differing degrees of light sensitivity, comprising in association with a higher sensitivity layer a yellow dye forming DIR coupler which releases a development inhibitor containing a weak inhibitor fragment having an Inhibitor Strength value less than 50, and further comprising in association with the lower sensitivity layer a cyan dye forming DIR coupler with a timing group containing a strong inhibitor fragment having an Inhibitor Strength value of 50 or more which releases a precursor of the development inhibitor fragment. This layer arrangement provides the ability to inhibit the red- and the blue-sensitive layers to the desired degree as a function of the green-sensitive layer development and and thereby provides improved color rendition. Detailed Description of the Invention The element of the present invention is comprised of a highly green-sensitive layer containing a yellow dye-forming development inhibitor releasing (DIR) coupler which releases a weak inhibitor and a lower green sensitive layer containing a cyan dye forming DIR coupler having a timing group which releases a strong inhibitor. The coupler containing the weak inhibitor fragment forms a yellow dye upon coupling. This has the effect of offsetting the inhibiting effect that this inhibitor might have on the blue sensitive layer. increased formation of yellow dye in the green-sensitive layer. The fact that the inhibitor is weak serves to minimize the inhibiting effect on the green-sensitive layer from which the DIR is released and this helps to minimize the adverse effect on green speed. In a similar manner, the coupler containing the strong inhibitor with the timing group forms a cyan dye upon coupling. This cyan dye helps offset the inhibition of the formation of cyan dye in the red-sensitive layer as a result of the release of inhibitor in the green-sensitive layer. The presence of the timing group in conjunction with the strong inhibitor helps to minimize the inhibiting effect in the green-sensitive layer where it is released as a precursor which is not itself inhibiting. The precursor is thus free to migrate from the layer in which it was released. Couplers that form cyan dyes upon reaction with oxidized color developing agents are described in such representative patents and publications as: U.S. Pat. Nos. 2,772,162, 2,895,826, 3,002,836, 3,034,892, 2,474,293, 2,423,730, 2,367,531, 3,041,236, 4,883,746 and "Farbkuppler-eine Literaturübersicht," published in Agfa Mitteilungen, Band III, pp. 156-175 (1961). Preferably such couplers are phenols and naphthols that form cyan dyes on reaction with oxidized color developing agent. Couplers that form magenta dyes upon reaction with oxidized color developing agent are described in such representative patents and publications as: U.S. Pat; Nos. 2,600,788, 2,369,489, 2,343,703i 2,311,082, 3,152,896, 3,519,429, 3,062,653, 2,908,573 and "Farbkuppler-eine Literaturübersicht," published in Agfa Mitteilungen, Band III, pp. 126-156 (1961). Preferably such couplers are pyrazolones, pyrazolotriazoles, or pyrazolobenzimidazoles that form magenta dyes upon reaction with oxidized color developing agents. Couplers that form yellow dyes upon reaction with oxidized and color developing agent are described in such representative patents and publications as: U.S. Pat. Nos. 2,875,057, 2,407,210, 3,265,506, 2,298,443, 3,048,194, 3,447,928 and "Farbkuppler-eine Literaturübersicht," published in Agfa Mitteilungen, Band III, pp. 112-126 (1961). Such couplers are typically open chain ketomethylene compounds. The method for evaluating the inhibitor strength of an inhibitor releasing coupler is well known in the art. See for example U.S. Patent 5,006,448. In the present invention, DIRs containing inhibitor fragments with I.S. values of 50 or more are classified as strong inhibitors and those having such values less than 50 are classified as weak inhibitors. Development inhibitors are generally released imagewise from an incorporated DIR compound during processing of the exposed photographic element. To evaluate the intrinsic inhibition strength of such inhibitors, independent of DIR release, an imbibition test is used. This involves imbibing an exposed film strip with a solution containing a given concentration of the free inhibitor to be tested. Nitrogen burst agitation of the imbibing solution improves the repeatability and effectiveness of inhibitor incorporation. The measured strength obtained by this test serves as an important guide in selecting inhibitors for desired photographic acutance and color rendition improvements. Film samples for imbibition testing of inhibitors were prepared having the following schematic layer structure and using a silver bromoiodide emulsion containing 6.4 mole % iodide(numerical values denote coating coverages in mg/m 2 and the silver halide values are for equivalent weights of silver): Overcoat Gelatin - 2691; Bis(vinlylsulfonylmethyl) ether hardener at 1.75% by weight of total gelatin Cyan Layer Gelatin - 2691; Green-sensitized AgBrI 1615; Cyan dye forming coupler (C-1) 753 Film Support Poly(ethylene terephthalate) Film strips cut from this coated element were exposed through a graduated-density test object and a Kodak Wratten 99 (green) filter. Before development a strip was immersed at 38°C under nitrogen agitation in each of the separate prebaths containing a test inhibitor at 5 x 10 -5 M concentration in a pH 10 carbonate buffer plus 0.1% dimethylformamide. As controls, each test set included a check strip which was immersed in a prebath containing no inhibitor and strips immersed in prebaths containing the comparison inhibitors phenylmercaptotetrazole (CI-1) and ethylmercaptotetrazole (CI-2). Photographic processing was carried out at 38°C in the following steps: Inhibitor prebath 2 min Developer 2.75 min Stop 2 min Wash 2 min Bleach 2 min Wash 2 min Fix 2 min Wash 2 min Developer grams/liter K 2 SO 3 2.0 4-amino-3-methyl-N-ethyl-beta-hydroxyethylaniline sulfate 3.35 K 2 CO 3 30.0 KBr 1.25 KI 0.0006 adjust to pH = 10.0 Red light densitometric curves were plotted for each strip and an exposure step at which the no-inhibitor check showed a density close to 1.0 above fog was selected. The density of each test strip at this same exposure was noted and the inhibition strength number (I.S. No.) calculated using the equation: (Density of check - density of test) Density of check X 100 Larger I.S. numbers for given inhibitors indicate stronger inhibition resulting in less dye density formed. The preferred weak inhibitors usable in the invention are the benzotriazoles and alkylmercaptotetrazoles. Table I shows typical examples of weak inhibitors and their corresponding I.S. numbers. The strong inhibitors usable in the invention are preferably aryl and arylalkyl mercaptotetrazoles and aryl oxadiazoles. Suitable examples of the strong inhibitors and their corresponding I.S. numbers are as shown in Table II. Further examples of DIRs having weak and strong inhibitor groups are shown, for example, in U.S. Patent U.S. 5,006,448. The DIR in the green layer of lower sensitivity in the invention includes a timing group in addition to having a strong inhibitor. The timing group is joined to the coupler moiety at any of the positions from which groups released from couplers by reaction with oxidized color developing agent can be attached. Preferably, the timing group is attached at the coupling position of the coupler moiety so that upon reaction of the coupler with oxidized color developing agent the timing group will be displaced. However, the timing group can be attached to a non-coupling position of the coupler moiety from which it will be displaced as a result of reaction of the coupler with oxidized color developing agent. In the case where the timing group is at a non-coupling position of the coupler moiety, other groups can be in the coupling position, including conventional coupling-off groups or the same or different inhibitor fragments or precursors from that described in the invention. Alternatively, the coupler moiety can have a timing group at each of the coupling position and a non-coupling position. Accordingly, couplers used in this invention can release more than one mole of inhibitor or other photographically useful material per mole of coupler. These released fragments can be the same or different and can be released at the same or different times and rates. The timing group can be any organic group that will serve to connect the coupler to the inhibitor fragment or precursor moiety and which, after cleavage from the coupler, will cleave from the inhibitor moiety preferably by an intramolecular nucleophilic displacement reaction of the type described in, for example, U.S. Patent 4,248,962 or by electron transfer down a conjugated chain as described in, for example, U.S. Patent 4,409,323 (quinone-methide types). Timing groups utilizing the mechanism in which there is electron transfer down a conjugated chain are especially preferred. U. S. Patents 4,842,994 and 5,135,839 contain a detailed explanation of timing groups which may be suitable for use in the invention. The term "intramolecular nucleophilic displacement reaction" refers to a reaction in which a nucleophilic center of a compound reacts directly, or indirectly through an intervening molecule, at another site on the compound, which is an electrophilic center, to effect displacement of a group or atom attached to the electrophilic center. Such compounds have a nucleophilic group and an electrophilic group spatially related by the configuration of the molecule to promote reactive proximity. Preferably the nucleophilic group and the electrophilic group are located in the compound so that a cyclic organic ring, or a transient cyclic organic ring, can be easily formed by an intramolecular reaction involving the nucleophilic center and the electrophilic center. A useful illustrative class of timing group (T) is represented by the structure: -(Nu - X - E)- wherein: Nu is a nucleophilic group attached to a position on the coupler from which it will be displaced upon reaction of the coupler with oxidized color developing agent, E is an electrophilic group attached to the inhibitor fragment as described and is displaceable therefrom by Nu after Nu is displaced from the coupler; and X is a linking group for spatially relating Nu and E, upon displacement of Nu from the coupler, to undergo an intramolecular nucleophilic displacement reaction with the formation of a 3- to 7 (preferably 5- or 6-) -membered ring and thereby release the inhibitor fragment. A nucleophilic group (Nu) is understood to be a grouping of atoms wherein one of which is electron rich. This atom is referred to as the nucleophilic center. An electrophilic group (E) is understood to be a grouping of atoms wherein one of which is electron deficient. This atom is referred to as the electrophilic center. In photographic couplers as described, the timing group can contain a nucleophilic group and an electrophilic group that are spatially related with respect to one another by a linking group so that upon release from the coupler moiety, the nucleophilic center and the electrophilic center will react to effect displacement of the inhibitor moiety from the timing group. The nucleophilic center should be prevented from reacting with the electrophilic center until release from the coupler moiety and the electrophilic center should be resistant to external attack such as hydrolysis. Premature reaction can be prevented by attaching the coupler moiety to the timing group at the nucleophilic center or at an atom in conjunction with a nucleophilic center, so that cleavage of the timing group and the inhibitor moiety from the coupler moiety unblocks the nucleophilic center and permits it to react with the electrophilic center, or by positioning the nucleophilic group and the electrophilic group so that they are prevented from coming into reactive proximity until release. The timing group can contain additional substituents, such as additional photographically useful groups , or precursors thereof, which may remain attached to the timing group or be released. Representative Nu groups contain electron rich oxygen, sulfur and nitrogen atoms. Representative E groups contain electron deficient carbonyl, thiocarbonyl, phosphonyl and thiophosphonyl moieties. Other useful Nu and E groups will be apparent to those skilled in the art. Especially preferred are those timing groups having the structure: wherein X is hydrogen or one or more substituents independently selected from hydroxy, cyano, fluoro, chloro, bromo, iodo, nitro, alkyl, alkoxy, aryl, aryloxy, alkoxycarbonyl, aryloxycarbonyl, carbonamido and sulfonamide; and Q is -N= or -C(W)=; wherein W is an electron donating group characterized by a sigma-para value greater than 0 (as determined as described in , Journal of Medicinal Chemistry , Hansch and Leo, 16, 1207, (1973). Typical W groups are -NO2,-NHSO 2 CH 3 , -NHSO 2 C 16 H 33 , -NHCOCH 3 , -NHCOC 11 H 23 , -Cl, -Br, -OCH 3 , -OCH 2 CH 2 OCH 3 , etc. Other useful timing groups are described in U.S. Patents 4,737,451; 4,546,073; 4,564,587;4,618,571; 4,698,297 and European Published Patent Applications 167,168A, 255,085A, and 362,870A. The timing group can contain moieties and substituents that will permit control of one or more of the rates of reaction of the coupler with oxidized color developing agent, the rate of diffusion of the inhibitor fragment once it is released from the coupler, and the rate of release of the inhibitor. The timing group can contain added substituents, such as added photographically useful groups, that can remain attached to the timing group and be released independently. The timing groups can contain a ballast group. In a preferred embodiment of the invention, one or more of the green-sensitive layers contains a yellow colored magenta dye-forming masking coupler. Any coupler known for this purpose may be employed. The use of 4-arylazopyrazolone masking couplers is known in the art. See, for example, U.S. 2,455,170; U.S. 2,428,034; U.S. 2,808,329; U.S. 2,434,272; U.S. 2,704,711; U.S. 2,688,539; U.S. 3,796,574; U.S. 3,476,560; U.S. 4,427,763; EP 213,490; and U.S. 4,777,123 as well as the materials referenced in Research Disclosure December 1989, Section VII, Part G, Published by Kenneth Mason Publications, Ltd., Dudley Annex, 12A North Street, Emworth, Hampshire PO10 7DQ, England. These compounds have proven useful since they are yellow colored in nonexposed areas and magenta colored in exposed areas. Thus, while the magenta dye formed in a color negative photographic process has a small but significant unwanted absorption in the blue range, this may be balanced somewhat by the relative loss of blue absorption due to conversion of the mask color from yellow to magenta in the exposed areas. Then, an adjustment can be made to the spectral content of the light used to produce the positive from the negative to effectively cancel out the unwanted blue absorption which has become essentially constant across both the exposed and unexposed areas of the negative. In addition to MM-1 used in the examples and identified at the end of the examples, the following are examples of suitable masking couplers: The present invention has beneficial effects on color rendition where a two-layer green sensitive pack is employed but the best results are obtainable with the use of a three-layer green-sensitive pack or "triple coat". In such case, it is preferred to employ the weak inhibitor DIR in the high green-sensitive layer and the strong inhibitor DIR with a timing group in the mid-sensitivity layer. The materials of the invention can be used in any of the ways and in any of the combinations known in the art. Typically, the invention materials are incorporated in a silver halide emulsion and the emulsion coated as a layer on a support to form part of a photographic element. Alternatively, they can be incorporated at a location adjacent to the silver halide emulsion layer where, during development, they will be in reactive association with development products such as oxidized color developing agent. Thus, as used herein, the term "associated" signifies that the compound is in the silver halide emulsion layer or in an adjacent location where, during processing, it is capable of reacting with silver halide development products. To control the migration of various components, it may be desirable to include a high molecular weight hydrophobe or "ballast" group in the component molecule. Representative ballast groups include substituted or unsubstituted alkyl or aryl groups containing 8 to 42 carbon atoms. Representative substituents on such groups include alkyl, aryl, alkoxy, aryloxy, alkylthio, hydroxy, halogen, alkoxycarbonyl, aryloxcarbonyl, carboxy, acyl, acyloxy, amino, anilino, carbonamido, carbamoyl, alkylsulfonyl, arysulfonyl, sulfonamido, and sulfamoyl groups wherein the substituents typically contain 1 to 42 carbon atoms. Such substituents can also be further substituted. The photographic elements can be single color elements or multicolor elements. Multicolor elements contain image dye-forming units sensitive to each of the three primary regions of the spectrum. Each unit can comprise a single emulsion layer or multiple emulsion layers sensitive to a given region of the spectrum. The layers of the element, including the layers of the image-forming units, can be arranged in various orders as known in the art. In an alternative format, the emulsions sensitive to each of the three primary regions of the spectrum can be disposed as a single segmented layer. A typical multicolor photographic element comprises a support bearing a cyan dye image-forming unit comprised of at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler, a magenta dye image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler, and a yellow dye image-forming unit comprising at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler. The element can contain additional layers, such as filter layers, interlayers, overcoat layers, subbing layers, and the like. If desired, the photographic element can be used in conjunction with an applied magnetic layer as described in Research Disclosure, November 1992, Item 34390 published by Kenneth Mason Publications, Ltd., Dudley Annex, 12a North Street, Emsworth, Hampshire PO10 7DQ, ENGLAND. In the following discussion of suitable materials for use in the emulsions used in the elements of this invention, reference will be made to Research Disclosure, December 1989, Item 308119, available as described above, which will be identified hereafter by the term "Research Disclosure". The Sections hereafter referred to are Sections of the Research Disclosure. The silver halide emulsions employed in the elements of this invention can be either negative-working or positive-working. Suitable emulsions and their preparation as well as methods of chemical and spectral sensitization are described in Sections I through IV. Color materials and development modifiers are described in Sections VII and XXI. Vehicles are described in Section IX, and various additives such as brighteners, antifoggants, stabilizers, light absorbing and scattering materials, hardeners, coating aids, plasticizers, lubricants and matting agents are described , for example, in Sections V, VI, VIII, X, XI, XII, and XVI. Manufacturing methods are described in Sections XIV and XV, other layers and supports in Sections XIII and XVII, processing methods and agents in Sections XIX and XX, and exposure alternatives in Section XVIII. Photographic elements can be exposed to actinic radiation, typically in the visible region of the spectrum, to form a latent image and can then be processed to form a visible dye image. Processing to form a visible dye image includes the step of contacting the element with a color developing agent to reduce developable silver halide and oxidize the color developing agent. Oxidized color developing agent in turn reacts with the coupler to yield a dye. With negative-working silver halide, the processing step described above provides a negative image. The described elements can be processed in the known C-41 color process as described in The British Journal of Photography Annual of 1988, pages 191-198. Preferred color developing agents are p-phenylenediamines such as: 4-amino-N,N-diethylaniline hydrochloride, 4-amino-3-methyl-N,N-diethylaniline hydrochloride, 4-amino-3-methyl-N-ethyl-N-(b-(methanesulfonamido) ethyl)aniline sesquisulfate hydrate, 4-amino-3-methyl-N-ethyl-N- (b-hydroxyethyl) aniline sulfate, 4-amino-3-b- (methanesulfonamido) ethyl-N,N-diethylaniline hydrochloride and 4-amino-N-ethyl-N- (2-methoxyethyl)-m-toluidine di-p-toluene sulfonic acid. Development is usually followed by the conventional steps of bleaching, fixing, or bleach-fixing, to remove silver or silver halide, washing, and drying. Examples The following example will serve to illustrate the invention further. The formulas for the component materials are provided following the example. Photographic Example 1 A color photographic recording material (Photographic Sample 101) for color negative development was prepared by applying the following layers in the given sequence to a transparent support of cellulose triacetate. The quantities of silver halide are given in grams of silver per m 2 . The quantities of other materials are given in grams per m 2 . Layer 1 {Antihalation Layer} black colloidal silver sol containing 0.236 g of silver, with 2.44 g gelatin. Layer 2 {First (least) Red-Sensitive Layer} Red sensitized silver iodobromide emulsion [1.3 mol % iodide, average grain diameter 0.55 µm (microns), average grain thickness 0.08 µm (microns) at 0.22 g, red sensitized silver iodobromide emulsion [4 mol % iodide, average grain diameter 1.0 µm (microns), average grain thickness 0.09 µm (microns) at 0.33 g, cyan dye-forming image coupler C-1 at 0.56 g, BAR compound B-1 at 0.089 g, with gelatin at 1.83 g. Layer 3 { Second (more) Red-Sensitive Layer } Red sensitive silver iodobromide emulsion [4 mol % iodide, average grain diameter 1.3 µm (microns), average grain thickness 0.12 µm (microns) at 0.56 g, cyan dye-forming image coupler C-1 at 0.23 g, cyan dye-forming masking coupler CM-1 at 0.022 g, DIR compound D-2 at 0.011 g, with gelatin at 1.66 g. Layer 4 { Third (most) Red-Sensitive Layer } Red sensitized silver iodobromide emulsion [4 mol % iodide, average grain diameter 2.6 µm (microns), average grain thickness 0.13 µm (microns) at 1.22 g, cyan dye-forming image coupler C-1 at 0.18 g, cyan dye-forming masking coupler CM-1 at 0.050 g, DIR compound D-6 at 0.003 g, DIR compound D-2 at 0.050 g, with gelatin at 1.36 g. Layer 5 { Interlayer } Yellow dye material YD-1 at 0.11 g and 1.33 g of gelatin Layer 6 { First (least) Green-Sensitive Layer } Green sensitized silver iodobromide emulsion [4 mol % iodide, average grain diameter 1.0 µm (microns), average grain thickness 0.09 µm (microns) at 0.78 g, magenta dye-forming image coupler M-2 at 0.22 g, magenta dye-forming image coupler M-3 at 0.089 g with gelatin at 1.78 g. Layer 7 { Second (more) Green-Sensitive Layer } Green sensitized silver iodobromide emulsion [4 mol % iodide, average grain diameter 1.25 µm (microns), average grain thickness 0.12 µm (microns) at 1.00 g, magenta dye-forming image coupler M-2 at 0.089 g, magenta dye-forming image coupler M-3 at 0.028 g, magenta dye-forming masking coupler MM-1 at 0.089 g with gelatin at 1.48 g. Layer 8 { Third (most) Green-Sensitive Layer ) Green sensitized silver iodobromide emulsion [4 mol % iodide, average grain diameter 2.16 µm (microns), average grain thickness 0.12 µm (microns) at 1.00 g, magenta dye-forming image coupler M-2 at 0.089 g, magenta dye-forming image coupler M-3 at 0.028 g, magenta dye-forming masking coupler MM-1 at 0.044 g, DIR compound D-3 at 0.008, DIR compound D-4 at 0.008 g with gelatin at 1.33 g. Layer 9 { Interlayer } Yellow dye material YD-2 at 0.11 g with 1.33 g gelatin. Layer 10 { First (less) Blue-Sensitive Layer } Blue sensitized silver iodobromide emulsion [1.3 mol % iodide, average grain diameter 0.55 µm (microns), average grain thickness 0.08 µm(microns) at 0.11 g, blue sensitized silver iodobromide emulsion [4 mol % iodide, average grain diameter 1.25 µm (microns), average grain thickness 0.12] at 0.26 g, blue sensitized silver iodobromide emulsion [6 mol % iodide, average grain diameter 1.0 µm (microns), average grain thickness 0.26 µm (microns) at 0.26 g, yellow dye forming image coupler Y-2 at 0.94 g, DIR compound D-5 at 0.049 g, BAR compound B-1 at 0.003 g with gelatin at 2.6 g. Layer 11 { Second (more) Blue-Sensitive Layer } Blue sensitized silver iodobromide emulsion [4 mol % iodide, average grain diameter 3.0 µm (microns), average grain thickness 0.14 µm (microns) at 0.39 g, blue sensitized silver iodobromide emulsion [9 mol % iodide, average grain diameter 1.0] at 0.39 g, yellow dye-forming image coupler Y-2 at 0.28 g, DIR compound D-5 at 0.044 g, BAR compound B-1 at 0.006 g with gelatin at 1.97 g. Layer 12 { Protective Layer } 0.106 g of dye UV-1, 0.106 g of dye UV-2, unsensitized silver bromide Lippman emulsion at 0.222 g, 2.03 g. This film was hardened at coating with 2% by weight to total gelatin of hardener H-1. Surfactants, coating aids, scavengers, soluble absorber dyes and stabilizers were added to the various layers of this sample as is commonly practiced in the art. Photographic Sample 102 was prepared like Photographic Sample 101 except DIR compound D-4 was added to layer 7 at 0.011 g. Photographic Sample 103 was prepared like Photographic Sample 101 except DIR compound D-4 was added to layer 7 at 0.022 g. Photographic Sample 104 was prepared like Photographic Sample 101 except DIR compound D-1 was added to layer 7 at 0.009g. Photographic Sample 105 was prepared like Photographic Sample 101 except DIR compound D-1 was added to layer 7 at 0.018 g. Photographic Sample 106 was prepared like Photographic Sample 101 except DIR compound D-1 was added to layer 7 at 0.027 g. DIR Variation In the Mid-Green Sensitive Layer With Weak DIR in Most Green-Sensitive Layer Sample Type Coupler in mid-green Level (g/m 2 ) R r /R n G g /G n B b /B n 101 Comp None 0 1.14 1.73 1.38 102 Comp D-4 0.011 1.20 1.69 1.38 103 Comp D-4 0.022 1.26 1.78 1.38 101 Comp None 0 1.14 1.73 1.38 104 Inv D-1 0.009 1.16 1.74 1.46 105 Inv D-1 0.018 1.18 1.78 1.56 106 Inv D-1 0.027 1.18 1.77 1.61 a) R r /R n - red separation gamma divided by red neutral gamma. b) G g /G n - green separation gamma divided by green neutral gamma. c) B b /B n - blue separation gamma divided by blue neutral gamma The controlling principal of the data is that a neutral exposure will cause exposure and development of the adjacent color records. This, in turn, will allow the adjacent records to release inhibitor which can migrate to the record of interest and thereby inhibit the development in the layer of interest. The gamma of the color of interest is therefore suppressed. By comparison, exposure of the element to a monochrome which affects only one color record will not cause the release of the inhibitors in adjacent records, and thus the monochrome exposure represents a noninhibited mode from an inter-image standpoint. Without inhibition, the ratio would be one. With increasing inhibition due to inter-image effects, the ratio increases due to the reduction in neutral gamma. As shown by the photographic data presented in Table III, the photographic samples incorporating weak inhibitor DIR compound D-4 in the most green-sensitive layer and containing the same weak inhibitor DIR compound in the lower sensitive layer exhibit increased inhibition of the red record without any significant increase in the inhibition of the blue record. This combination does not achieve the desired inhibition effect on the blue record. On the other hand, the photographic samples incorporating the strong inhibitor DIR containing a timing group, compound D-1, in the lower green-sensitive layer exhibit had the effect of increasing blue inhibition as a result of green exposure while maintaining the red inhibition. This is the desired objective. Photographic Example 2 A color photographic recording material (Photographic Sample 107) for color negative development was prepared by applying the following layers in the given sequence to a transparent support of cellulose triacetate. The quantities of silver halide are given in g of silver per m 2 . The quantities of other materials are given in g per m 2 . Layer 1 {Antihalation Layer} black colloidal silver sol containing 0.236 g of silver, with 2.44 g gelatin. Layer 2 {First (least) Red-Sensitive Layer} Red sensitized silver iodobromide emulsion [1.3 mol % iodide, average grain diameter 0.55 µm (microns), average thickness 0.08 µm (microns) at 0.49 g, red sensitized silver iodobromide emulsion [4 mol % iodide, average grain diameter 1.0 µm (microns), average thickness 0.09 µm (microns) at 0.48 g, cyan dye-forming image coupler C-1 at 0.56 g, cyan dye-forming masking coupler CM-1 at 0.033 g, BAR compound B-1 at 0.039 g, with gelatin at 1.83 g. Layer 3 {Second (more) Red-Sensitive Layer} Red sensitive silver iodobromide emulsion [4 mol % iodide, average grain diameter 1.3 µm (microns), average grain thickness 0.12 µm (microns) at 0.72 g, cyan dye-forming image coupler C-1 at 0.23 g, cyan dye-forming masking coupler CM-1 at 0.022 g, DIR compound D-1 at 0.011 g, with gelatin at 1.66 g. Layer 4 {Third (most) Red-Sensitive Layer} Red sensitized silver iodobromide emulsion [4 mol % iodide, average grain diameter 2.6 µm (microns), average grain thickness 0.13 µm(microns) at 1.11 g, cyan dye-forming image coupler C-1 at 0.13 g, cyan dye-forming masking coupler CM-1 at 0.033 g, DIR compound D-1 at 0.024 g, DIR compound D-2 at 0.050 g, with gelatin at 1.36 g. Layer 5 {Interlayer} Yellow dye material YD-1 at 0.11 g and 1.33 g of gelatin Layer 6 {First (least) Green-Sensitive Layer} Green sensitized silver iodobromide emulsion [1.3 mol % iodide, average grain diameter 0.55 µm (microns), average grain thickness 0.08 µm (microns) at 0.62 g, green sensitized silver iodobromide emulsion [4 mol % iodide, average grain diameter 1.0 µm (microns), average grain thickness 0.09 µm (microns) at 0.32 g, magenta dye-forming image coupler M-1 at 0.24 g, magenta dye-forming masking coupler MM-1 at 0.067 g with gelatin at 1.78 g. Layer 7 {Second (more) Green-Sensitive Layer} Green sensitized silver iodobromide emulsion [4 mol % iodide, average grain diameter 1.25 µm (microns), average grain thickness 0.12 µm (microns) at 1.00 g, magenta dye-forming image coupler M-1 at 0.091 g, magenta dye-forming masking coupler MM-1 at 0.067 g, DIR compound D-1 at 0.024 g with gelatin at 1.48 g. Layer 8 {Third (most) Green-Sensitive Layer) Green sensitized silver iodobromide emulsion [4 mol % iodide, average grain diameter 2.16 µm (microns), average grain thickness 0.12 µm (microns) at 1.00 g, magenta dye-forming image coupler M-1 at 0.0.72 g, magenta dye-forming masking coupler MM-1 at 0.056 g, DIR compound D-3 at 0.01 g, DIR compound D-4 at 0.011 g, with gelatin at 1.33 g. Layer 9 {Interlayer} Yellow dye material YD-2 at 0.11 g with 1.33 g gelatin. Layer 10 {First (less) Blue-Sensitive Layer} Blue sensitized silver iodobromide emulsion [1.3 mol % iodide, average grain diameter 0.55, average grain thickness 0.08 µm (microns) at 0.24 g, blue sensitized silver iodobromide emulsion [6 mol % iodide, average grain diameter 1.0 µm (microns), average grain thickness 0.26 µm (microns) at 0.61 g, yellow dye-forming image coupler Y-1 at 0.29 g, yellow dye forming image coupler Y-2 at 0.72 g, cyan dye-forming image coupler C-1 at 0.017 g, DIR compound D-5 at 0.067 g, BAR compound B-1 at 0.003 g with gelatin at 2.6 g. Layer 11 {Second (more) Blue-Sensitive Layer} Blue sensitized silver iodobromide emulsion [4 mol % iodide, average grain diameter 3.0 µm (microns), average grain thickness 0.14 µm(microns) at 0.23 g, blue sensitized silver iodobromide emulsion [9 mol % iodide, average grain diameter 1.0 µm (microns) at 0.59 g, yellow dye-forming image coupler Y-1 at 0.090 g, yellow dye-forming image coupler Y-2 at 0.23 g, cyan dye-forming image coupler C-1 0.022 g, DIR compound D-5 at 0.05 g, BAR compound B-1 at 0.006 g with gelatin at 1.97 g. Layer 12 {Protective Layer} 0.111 g of dye UV-1, 0.111 g of dye UV-2, unsensitized silver bromide Lippman emulsion at 0.222 g, 2.03 g. This film was hardened at coating with 2% by weight to total gelatin of hardener H-1. Surfactants, coating aids, scavengers, soluble absorber dyes and stabilizers were added to the various layers of this sample as is commonly practiced in the art. Photographic Sample 108 was prepared like Photographic Sample 107 except layer 8 had a level of magenta dye-forming masking coupler of 0.028 g. Photographic Sample 109 was prepared like Photographic Sample 107 except layer 7 had a level of magenta dye-forming masking coupler of 0.033 g. Photographic Sample 110 was prepared like Photographic Sample 107 except layer 6 had a level of magenta dye-forming masking coupler of 0.033 g. Tests were conducted to reveal the effect of the inclusion or absence of a yellow-colored magenta masking coupler on the ability of this combination with the couplers usable in the invention to effect the desired effect on the blue sensitive layer. These results are shown in Table II. Effect of Yellow-Colored Magenta Dye-Forming Masking Coupler Sample Layers Containing Mask Lower B b /B n Mid B b /B n Mid Upper B b /B n 107 H,M,L 1.10 1.53 1.33 108 M,L 1.06 1.46 1.33 109 H,L 1.12 1.44 1.25 110 H,M 1.12 1.49 1.21 a) Low B b /B n - blue separation gamma divided by blue neutral gammaa between Dmin+0.15 density and 0.4 logE slow of that point. b) Mid B b /B n - blue separation gamma divided by blue neutral gammab between 0.40 logE slow of Dmin+0.15 density and 1.1 logE slow of Dmin+0.15 density. c) Mid Upper B b /B n - blue separation gamma divided by blue neutral gammab between 1.1 logE slow of Dmin+0.15 density and 1.8 logE slow of Dmin+0.15 density. As demonstrated by the photographic data presented in Table IV, by employing the DIR couplers usable in the invention and also distributing a masking coupler in the most, mid, and least green-sensitive silver halide emulsion layers, the interimage effect of blue inhibition as a result of green exposure can be controlled throughout the desired exposure region to improve color rendition. In reviewing all the data, it is apparent that an untimed yellow dye-forming DIR coupler which releases a weak inhibitor fragment, such as D-4, can be used in the more green-sensitive silver halide emulsion layer to control red inhibition, and a cyan dye-forming DIR coupler with a timing group and containing a strong inhibitor fragment, such as D-1, can be used in the lower green-sensitive silver halide emulsion layer to control blue inhibition. Further, a masking coupler, such as MM-1, can be distributed in one or more of the green-sensitive silver halide emulsion layers to balance the interimage inhibition of blue as a result of green exposure over the desired exposure region. The formulas for the component materials are as follows: H-1: CH 2 (SO 2 CH=CH 2 ) 2

Claims: A photographic element comprising at least two light sensitive silver halide layers sensitized to green light and having differing degrees of light sensitivity, characterized in that there is in association with a higher sensitivity layer a yellow dye forming DIR coupler which releases a development inhibitor containing a weak inhibitor fragment having an Inhibitor Strength value less than 50, and there is in association with a lower sensitivity layer a cyan dye forming DIR coupler with a timing group containing a strong inhibitor fragment having an Inhibitor Strength value of 50 or more which releases a precursor of the development inhibitor fragment. The element of Claim 1 wherein the DIR containing the weak inhibitor contains an inhibitor fragment having a structure selected from the following: The element of Claim 1 wherein the DIR containing a strong inhibitor contains an inhibitor fragment selected from the group consisting of the following: The element of Claim 1 wherein the weak inhibitor fragment is a benzotriazole or alkylmercaptotetrazole. The element of Claim 1 wherein the strong inhibitor fragment is a phenylmercaptotetrazole. The element of any of claims 1-5 wherein the DIR with a timing group contains a quinone methide timing group. The element of any of claims 1-6 wherein the yellow dye-forming coupler is contained in the most sensitive layer. The element of any of claims 1-7 in which the element comprises three green light sensitive layers having higher, mid- and lower sensitivity to light wherein the cyan dye-forming coupler is contained in the mid-sensitive layer. The element of any of claims 1-8 containing a yellow colored magenta dye-forming masking coupler in at least one of said green sensitive layers. The element of Claim 9 wherein the masking coupler is selected from the following:

Inventors: MERRILL JAMES PARKER, MERRILL, JAMES PARKER, MERRILL, JAMES PARKER, C/O EASTMAN KODAK COMPANY
Applicants: EASTMAN KODAK CO, EASTMAN KODAK COMPANY
Application year: 1994
Main classification: G03C7
IPC codes: G03C7